Question: $\left(-10x - 7\right)^2 = \ ?$
Solution: $= \left(-10x - 7\right)\left(-10x - 7\right)$ $= -10x \cdot \left(-10x - 7\right) - 7 \cdot \left(-10x - 7\right)$ $= \left( -10x \cdot -10x \right) + \left( -10x \cdot -7 \right) + \left( -7 \cdot -10x \right) + \left( -7 \cdot -7 \right)$ $= 100x^2 + \left( -10x \cdot -7 \right) + \left( -7 \cdot -10x \right) + \left( -7 \cdot -7 \right)$ $= 100x^2 + \left( 70x + 70x \right) + \left( -7 \cdot -7 \right)$ $= 100x^2 + 140x + \left( -7 \cdot -7 \right)$ $= 100x^2 + 140x + 49$